title: Microbial communities along biogeochemical gradients in a hydrocarbon-contaminated aquifer.
abstract: Micro-organisms are known to degrade a wide range of toxic substances. How the environment shapes microbial communities in polluted ecosystems and thus influences degradation capabilities is not yet fully understood. In this study, we investigated microbial communities in a highly complex environment: the capillary fringe and subjacent sediments in a hydrocarbon-contaminated aquifer. Sixty sediment sections were analysed using terminal restriction fragment length polymorphism (T-RFLP) fingerprinting, cloning and sequencing of bacterial and archaeal 16S rRNA genes, complemented by chemical analyses of petroleum hydrocarbons, methane, oxygen and alternative terminal electron acceptors. Multivariate statistics revealed concentrations of contaminants and the position of the water table as significant factors shaping the microbial community composition. Micro-organisms with highest T-RFLP abundances were related to sulphate reducers belonging to the genus Desulfosporosinus, fermenting bacteria of the genera Sedimentibacter and Smithella, and aerobic hydrocarbon degraders of the genus Acidovorax. Furthermore, the acetoclastic methanogens Methanosaeta, and hydrogenotrophic methanogens Methanocella and Methanoregula were detected. Whereas sulphate and sulphate reducers prevail at the contamination source, the detection of methane, fermenting bacteria and methanogenic archaea further downstream points towards syntrophic hydrocarbon degradation.
authors.affiliation: Department of Environmental Microbiology, Helmholtz Centre for Environmental Research--UFZ, Permoserstr. 15, 04318, Leipzig, Germany.
authors.forename: Karolin
authors.initials: K
authors.lastname: Tischer
authors.forename: Sabine
authors.initials: S
authors.lastname: Kleinsteuber
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Schleinitz
authors.forename: Ingo
authors.initials: I
authors.lastname: Fetzer
authors.forename: Oliver
authors.initials: O
authors.lastname: Spott
authors.forename: Florian
authors.initials: F
authors.lastname: Stange
authors.forename: Ute
authors.initials: U
authors.lastname: Lohse
authors.forename: Janett
authors.initials: J
authors.lastname: Franz
authors.forename: Franziska
authors.initials: F
authors.lastname: Neumann
authors.forename: Sarah
authors.initials: S
authors.lastname: Gerling
authors.forename: Christian
authors.initials: C
authors.lastname: Schmidt
authors.forename: Eyk
authors.initials: E
authors.lastname: Hasselwander
authors.forename: Hauke
authors.initials: H
authors.lastname: Harms
authors.forename: Annelie
authors.initials: A
authors.lastname: Wendeberg
mesh_terms: D001105:Archaea / Q000145:classification / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000378:metabolism; D018407:Bacterial Physiological Phenomena; D044822:Biodiversity; D005858:Germany; D060587:Groundwater / Q000737:chemistry / Q000382:microbiology*; D006838:Hydrocarbons / Q000032:analysis* / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D014871:Water Microbiology; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism
chemical_list: D006838:Hydrocarbons; D012336:RNA, Ribosomal, 16S; D014874:Water Pollutants, Chemical